Maximum head
The maximum head generated by the pump. This parameter is most often indicated in meters, by the height of the water column that the unit can create — in other words, by the height to which it can supply water. You can estimate the pressure created by the pump using a simple formula: every 10 m of head corresponds to a pressure of 1 bar.
It is worth choosing a pump according to this parameter, taking into account the height to which it should supply water, as well as adjusting for losses and the need for pressure in the water supply. To do this, it is necessary to determine the difference in height between the water level and the highest point of water intake, add another 10 to 30 m to this figure (depending on the pressure that needs to be obtained in the water supply), and multiply the result by 1.1 — this will be the minimum pressure required.
Grinder
A device for grinding large mechanical impurities contained in the pumped liquid.
The grinder is installed at the pump inlet, in front of the main mechanism. Its task is to protect this mechanism from jamming and/or damage: the grinder crushes the impurities contained in the water into small particles, which the pump itself can handle without any problems.
This function is most relevant when working with heavily contaminated liquids; so most units with grinders are designed for dirty water or sewerage (see “Suitable for”). At the same time, a similar function can also be found in models for clean water — it increases overall reliability and provides an additional guarantee in case large particles do end up in the water.
Maximum power
Rated power of the pump motor. The more powerful the engine, the higher the performance of the unit, usually, the greater the pressure, suction height, etc. Of course, these parameters largely depend on other features (primarily the pump type, see above); but models similar in design can be compared in terms of power.
Note that high power, usually, increases the size, weight and cost of the pump, and also implies high costs of electricity or fuel (see "Power source"). Therefore, it is worth choosing a pump according to this parameter taking into account the specific situation; more detailed recommendations can be found in special sources.
